EP1538367B1 - Damper valve assembly with a progressive damping force characteristic - Google Patents

Abstract

The assembly has a damping valve (12) which opens as a flow velocity of a damping medium increases in an operating range. A control slide (41) moves in a closing direction to close a throttle in another operating range with a progressive damping characteristic. The control slide has a pressure-actuated surface which acts in the closing direction as a function of the flow velocity of the damping medium.

Description

The invention relates to a Dämpfventileinrichtung according to the preamble of claim 1.

DE 35 33 386 A1 describes a two-pipe vibration damper whose piston carries a compression spring, the stroke-dependent moves a spool on a bottom valve in a closed position to produce a progressive Dämpfkraftkennlinie shortly before the stroke end of the piston. In vehicles that are moved at a comparatively high speed on a poor road, the case may occur that the wheel abruptly rebounds and is braked with a maximum damping force, which is determined by a valve disc set on the bottom valve, in its further compression movement. Then hits the stop spring on the bottom valve-side spool, only a relatively small Resthubweg, which is available for energy dissipation of the springing wheel remains. In this case, it may happen that the vehicle body is damaged in the area of the vibration damper connection.

The easiest option at first glance is certainly simply to reinforce the vehicle body in the hazardous area, but this would require a noticeable increase in weight.

Another disadvantage of this principle is that a real loss of lift occurs due to the piston-side stop spring. In this context, nor to mention DE 36 02 224 A1, which describes the same principle of action.

DE 31 07 517 A1 discloses a vibration damper whose Dämpfventileinrichtung comprises two valves which are hydraulically connected in parallel. A first damping valve comprising a throttle cross-section, which increases with increasing piston rod speed of a valve body, for. B. an elastic disc, is reduced in dependence on the piston rod speed, so that a progressive Dämpfkraftkennlinie is achieved. In the case of overload, a pressure relief valve can be used, which connects the two working spaces of the vibration damper. In practice, different solutions occur in a solution according to DE 31 07 517 A1. Thus, the damping force at comparatively low speeds is very small and increases parabolic, so that when driving a rather spongy and inaccurate driving feeling is noticeable. Even at low speeds you want to feel a certain amount of damping force, which then follows in a medium piston speed range of a degressive or linear Dämpfkraftkennlinie and only at very high piston speeds a progressive damping force shows the day. Such Dämpfkraftkennlinie can with a small, often constantly open Voröffnungsquerschnitt and a hydraulically connected in parallel spring-biased damping valve can be achieved, which opens from a defined piston speed.

Object of the present invention, it is to realize a Dämpfventileinrichtung having a Dämpfkraftkennlinie with a progressively increasing proportion, but in a Kennymiebereich corresponding to a normal operation, a vehicle-compatible Dämpfkraftkennlinie follows.

According to the invention the object is achieved in that the spool has a pressurized by the damping medium surface which acts in the closing direction of the spool in dependence on the flow rate of the damping medium.

The great advantage of the invention is that a conventional damping valve can be used as a basis, the damping force characteristic is tuned to the normal operation and both comfort and safety requirements. Through the use of the spool, a damping force characteristic can be achieved in addition at higher suspension speeds, which is independent of the current level position of the wheel and independent of the sub-range of the damping force characteristic of normal operation, so that no loss of comfort can be recorded.

Furthermore, it is provided that the spool is arranged in relation to the flow path of the damping medium in series with the damping valve. It closes the inflow or outflow of damping medium at the damping valve, so as to achieve a total of a damping force increase.

In a further embodiment of the invention, it is provided that the spool is connected with its pressurized surface to a throttle point, which leads to the first Dämpfventilbaugruppe. This allows a space-saving construction of the entire damping valve can be achieved.

Thus, the throttle point is determined by the outer diameter of the spool.

To ensure a defined operating behavior of the spool, the spool is held by a spring in passage position.

To protect the Dämpfventileinrichtung, but also a vibration damper, in which the Dämpfventileinrichtung is used, the throttle body, a pressure relief valve is connected in parallel. This allows the achievable damping force of the damping valve to be limited to a defined level.

In one embodiment, the pressure relief valve is formed by a spring disk package that also holds the spool in the forward position. Overall, there is a very flat-building unit.

Alternatively, the spool is held in the forward position regardless of the biasing force acting on the pressure relief valve. This variant allows greater freedom of design in determining the damping force characteristic.

For this purpose, the spool is slidably mounted relative to the valve disc of the pressure relief valve. From space economy, the valve disc of the pressure limiting valve is arranged coaxially to the spool.

In a further constructive embodiment, the spool is axially supported in the passage position on the valve disc of the pressure relief valve.

In order to use as close as possible components for the first assembly of the damping valve, a spring carrier takes on the control slide in the passage position holding spring.

Overall, the damping valve must be made very precise in terms of the desired effect. So that unavoidable manufacturing tolerances do not impair the function, the valve body has a plastically deformable adjustment range.

The adjustment region of the valve body is formed by a wall thickness reduction. In the manufacturing process, the spool is controlled biased in the closed position, wherein depending on the existing manufacturing tolerances, a deformation of the spool takes place and the passage cross section of the throttle point is set.

Furthermore, the throttle point is determined by an inner wall of a cylinder of a vibration damper. This spatial design allows the use of very simple spool components, since the cylinder is usually already designed as a precision component.

According to an advantageous subclaim, the damping valve device is designed on a piston of a vibration damper. Would you the inventive damping valve z. B. run as a bottom valve at a vibration damper, then only the displaced volume of the retracting piston rod would be available for Dämpfkrafterzeugung available. If, however, the invention according to the damping valve on a piston, for. B. for the insertion direction of the piston executes, then possibly the Dämpfmediumvolumen the entire displaced cylinder cross-section used for Dämpfkrafterzeugung, wherein the cavitation formation is taken in the then increasing space for the certainly rarely occurring case in purchasing.

In this case, the spool affects the Dämpfmediumzu- and effluent on the piston.

The spool is supported on a piston nut of the piston. The entire length of the piston is not extended by the damping valve according to the invention.

In order to be able to more accurately tune the damping force characteristic curve for the normal operation of the damping valve, the spring holding the control slide in the passage position is independently of a valve spring biasing the valve body of the first damper valve assembly of the piston-side damper valve.

The valve spring for the first assembly of the damping valve fixes the damper assembly comprising the assembly to the damping valve. You can the spring carrier for the spring of the spool z. B. stiffen or weld to the piston nut. On the other hand, the usual spring force of the valve spring tends to be so great that this spring force can bias the spring carrier against the force of the force acting on the spool spring on the piston nut.

For the production, it is advantageous, in particular for maintaining the cycle time, if as far as possible prefabricated units are used. Therefore, the piston nut of the spring carrier and the spool are braced to form a unit.

In addition, the assembly may be assigned a support ring on which the spool is axially supported. This counteracts a misalignment of the spool in the passage position.

According to an advantageous embodiment, the support ring is connected to transmit torque to the piston nut and executed with Verdichtwerkzeugflächen. The piston nut has the mounting thread to the piston rod, but the shell surface, on which usually the hexagon profile is executed, is covered by the spring carrier and the spool. With the new variant, the piston nut can be screwed over the support ring.

The invention will be explained in more detail with reference to the following description of the figures.

Fig. 1

Darstellung des erfindungsgemäßen Dämpfventil als Kolben- oder Bodenventil in einem Schwingungsdämpfer

Fig. 2

Detaildarstellung eines Druckbegrenzungsventils

Fig. 3

Variante von einem Kolbenventil nach Fig. 1

Fig. 4

Steuerschieber mit einem Justierbereich

Fig. 5

Steuerschieber mit unabhängig vorgespanntem Druckbegrenzungsventil

Fig. 6

Dämpfkraftkennlinie des erfindungsgemäßen Dämpfventils

It shows:

Fig. 1

Representation of the damping valve according to the invention as a piston or bottom valve in a vibration damper

Fig. 2

Detail of a pressure relief valve

Fig. 3

Variant of a piston valve according to FIG. 1

Fig. 4

Spool with an adjustment range

Fig. 5

Spool with independently preloaded pressure relief valve

Fig. 6

Dämpfkraftkennlinie the damping valve according to the invention

1 shows a section of a vibration damper 1, in which filled with a damping medium cylinder 3, a piston rod 5 to which a piston 7 is fixed, is guided axially movable. The piston 7 divides the cylinder 3 in a piston rod side and a piston rod remote working space 9; 11. In the piston groups of passageways 13 for both flow directions of the damping medium; 15 executed. A first assembly 10 of a damping valve 12 includes for the retraction movement of the piston into the cylinder, the passage channels 15, the outlet ends on the upper side of the piston 7 of at least one valve disc 17 are at least partially covered in conjunction with a valve spring 19. In a vibration damper according to the Einrohrbauprinzip this first assembly - passageways 15; Valve disc 17 and valve spring 19 - determine the damping force characteristic for normal operation. Within the valve disc 19 or the valve seat surface on the piston top side, a very small, not shown permanently opened Voröffnungsquerschnitt be executed, which is effective only at low flow or piston speeds. Above a defined piston speed, the valve disc 17 lifts off the valve seat surface and releases the passage channels 15.

For the damping of the extension direction are running on the smaller pitch circle diameter passages 13 are available, which are also at least partially covered by a valve body 21 which is biased by a valve spring 23. The valve spring 23 is supported on a piston nut 25, which is in threaded engagement with a piston rod pin. These described parts forming the second assembly 14 of the damping valve 12, wherein the assemblies 10; 14 of the damping valve 12 correspond to a standard used damping valve on a piston.

Furthermore, in a vibration damper according to the monotube principle, in a vibration damper according to the two-pipe principle, there is a standard Dämpfventileinrichtung in the design of a bottom valve 27 are used, the valve body 29 also two groups of passageways 31; 33 has. On a larger circle the passageways 33 are for the Influx of a not shown on the underside of the valve body 29 damping agent filled space in the piston rod remote working space 11 is arranged. These passageways 33 are usually covered by a simple check valve in the execution of a disc 35 with a closing spring 37. The passageways 33, the disc 35 and the closing spring 37 form a first assembly 16 of the bottom valve 27. For the outflow from the piston rod remote working space 11 in the direction of the underside of the valve body 29, the valve body 29 via the passageways 31, of at least one elastic valve disc 39 are covered, this combination is to be regarded as the second assembly 18 of the Dämpfventileinrichtung 27. This structural design of a damping valve is known.

During a retraction movement of the piston rod displaced by the piston rod 5 damping medium volume is displaced by the second assembly 18 of the bottom valve 27 and generates a damping force. The first or second assembly 16; 18 correspond to the damping valve 20 on the piston, which merges with increasing flow velocity in a passage position.

The designed as a bottom valve damper valve device 27 also has an axially movable spool 41, the lower end face 42 may come to rest on the disc 35 of the check valve against a spring 43 in the form of an elastic disc. The spring 43 holds the spool 41 in a passage position, wherein the top of the disc 35 of the check valve and the lower end surface 42 of the spool 41 form a first throttle 45.

An annular, firmly riveted to the valve body 29 support body 47 receives the spring 43 on the inner diameter, said support body 47 and the closing spring 37 of the check valve is supported. The spring 43 is at the inner diameter with the support body 47 z. B. caulked and z is on the outer diameter. B. connected via a locking ring 49 with the spool 41, so that a backlash-free clamping of the spring 43 is present.

The spool 41 has at its outer diameter over a multi-stepped contour, wherein a first shoulder 51 with the inner wall 53 of the cylinder forms a second throttle point 55, at which a significant pressure drop is available. The axial extent of the first paragraph is deliberately chosen comparatively short in order to minimize temperature-induced viscosity effects within the second throttle body 55. The facing in the direction of the piston rod remote working chamber 11 end face can be used as a pressurized surface 57 which acts on the spool 41 in dependence on the flow velocity within the second throttle body 55 in the closing direction. The two throttle bodies 45; 55 are sized so that they do not exert any significant effect on the damping force characteristic of the entire damping valve within the normal operation of the vibration damper.

When the flow rate has reached a threshold and the spool 41 rests on the disc 35 of the check valve, so that the first throttle point 45 is closed, then one of the first restrictor 45 can open parallel-connected pressure relief valve 59. The pressure limiting valve 59 is formed in this embodiment of a spring disk package, namely the spring 43 which holds the spool 41 in the forward position and at least one cover plate 61 below the spring 43, wherein the spring 43 has at least one passage cross-section 62 which in normal operation of the damping valve of the cover plate 61 is closed.

It is essential that the closing movement of the spool 41 is dependent exclusively on the flow rate of the damping medium, ie on the retraction speed of the piston 7 and thus can be used in each stroke position. Furthermore, no Vorspannweg required by the piston 7 for the closing movement of the spool 41 on the bottom-side damper valve 27, so that the usable stroke for the damping forces occurring in emergency operation is very large.

Also on the piston rod 5, the damping valve device according to the invention may be performed, but it is still very useful to equip the bottom valve with a slide 41. In this case, the spool 41 is supported indirectly on the piston nut 25 and thus influences the Dämpfmediumzustrom in the piston 7. In addition, the piston nut carries a spring support 63 with an S-shaped cross section, which receives the spring 43, which biases the spool 41 in the forward direction , The spring 43 for the spool 41 is carried out independently of the valve spring 23 for the valve body 21, said valve spring 23 and the control spool 41 comprehensive assembly 22, namely the spring carrier 63 together with the spring 43 and the spool 41 can fix on the piston nut 25, which may still be a support ring 65 may be used.

With a correspondingly large piston speed, a pressure builds up in the piston rod-distant working chamber 11, which acts on the pressurized surface 57 of the spool 41 on the piston and moves it against the force of the spring 43 in the direction of an end face 67 of the piston 7. The upper side of the annular edge 69 of the spool 41 and the end face 67 of the piston 7 form the first throttle 45 and the outer diameter of the rim 71 with the inner wall 53 of the cylinder 3, the second throttle 55, wherein the pressure difference in the region of the second throttle 55, the closing behavior of the spool 41 is determined.

Also, on the piston 7, as shown in FIG. 2, parallel to the spool 41, a pressure relief valve 59 may be executed, which is formed for example by a cover plate 61 which covers the passage cross-section 62 within the spring carrier 63 depending on the direction.

In a combined arrangement of the Dämpfventileinrichtung on the piston and the bottom valve, the slider should take the closed position at a lower flow velocity, the closed position than the slide on the piston, since then can not have the effect that in a closed slide on the piston still a comparatively large cross-section on Bottom valve is available and the volume is pushed out of the piston rod remote working space through the bottom valve. One would leave with it damping force unused.

FIG. 3 shows a modification of FIG. 1. The difference is that the piston nut 25, the spring carrier 63, the spool 41 together with the spring 43 and the support ring 65 form a structural unit. For this purpose, the piston nut has a support surface 25s against which the cover plate 61 of the pressure limiting valve 59 rests. The inner diameter of the support ring 65 is profiled that upon a plastic deformation of a sleeve portion 25h of the piston nut 25, a projecting end is deformed on the underside of the support ring and in the profiling of the support ring, so that a torque-transmitting connection between the piston nut 25 and the support ring 65 is , On the outside, the support ring is provided with turning tool surfaces 65v, which make it easier to screw said assembly on the piston rod pin.

4 contains, inter alia, a modification of the spool 41 within the bottom valve 27. The annular spool 41 is held by a valve disc 64 in combination with the elastic cover plates 61 in a defined passage position. In particular, height tolerances of the individual components can cause the distance between the end face 42 and the disk 35 for the passageways 33 does not occupy the required level, whereby the effect of the throttle body 45 is changed. In order to minimize an error of this kind, it is provided that the said distance due to the dimensional design of the individual Components are always smaller than the nominal size for the correct setting of the throttle point 45.

Within the wall of the annular spool 41 at least one circumferential groove 41 n are incorporated on the inner and outer diameter as wall thickness reduction, which form a plastically deformable adjustment region 44. When adjusting the throttle point, the spool is pressed onto the top of the disc 35, wherein the spool is plastically deformed in the axial direction until the correct distance measure for the throttle point is present in the passage position. With this method, all the distance-determining errors can be compensated.

Fig. 5 shows a further development of the bottom valve 27 of FIG. 1, in which the bias of the cover plates 61 of the pressure limiting valve 59 is independent of the spring 43, which holds the spool 41 in the passage position. The spring 43 is designed as a disc spring whose inner diameter range between a bolt 73 and a clamping nut 75 is fixed to the valve body 29. Alternatively, a riveted joint according to FIG. 1 can also be used. The disc spring 43 acts on the underside of the locking ring 49. The support body 47 serves as a support for the cover plates 61, to which a valve spool 64 independent of the spool valve is pretensioned. A pressure ring 77 provides a tensioning chain from the support surface 79 of the support body on the cover plates 61 and the valve disc 64, the pressure ring 77 and the spring 43 to the clamping nut 75. The spool 41 is supported in the passage position axially on the underside of the valve disc 64 from . wherein the biasing force is generated by the spring 43. Overall, the spool 41 between the blocking position, end face 42 rests on the disc 35, and the passage position, spool is axially against the underside of the valve disc 64, slidably mounted to the cover plates 61. The bias of the cover plates 61 does not act on the spool so that there is no dependence on the Abhubbewegung the cover plates 61 of the valve disc 64 with respect to the performance of the spool.

6 shows the damping force characteristic curve damping force = f (flow velocity VD) of the damping valve according to the invention. At low flow velocities only the constantly open at many Dämpfventilkonstruktionen Voröffnungsquerschnitt, the z. B. is executed in the valve seat surface for the valve disc 17. As soon as the damping force has reached a certain level, depending on the direction of movement of the piston, one of the valve disks or valve body lifts off on the piston or on the bottom-side valve 27, whereby a linear or degressive characteristic curve in the normal range of the vibration damper tends to be sought in many cases. At extreme flow velocities in the damping valves, z. As in a rapid suspension movement of the vibration damper, the spool acts very strong damping force enhancing, starting from a defined Dämpfkraftniveau the pressure relief valve 59 opens.

Claims (23)

1. Damper-valve device, comprising a first damper valve (15; 17; 19; 29; 33; 35; 37) having a damper-force characteristic curve profile, in which a damper-valve body (17), in a first operating range as a function of the flow speed at the damper valve (15; 17; 19; 29; 33; 35; 37), moves into a throughflow operating position as the flow speed of a damper medium increases, having a second damper valve (41; 55) which has a progressive damper-force characteristic in a second operating range of the damper-force characteristic curve profile and the throttle point (55) of which can be transferred into a closed position in conjunction with a control slide (41), characterized in that the control slide (41) has a surface (57) which is loaded with pressure by the damper medium and acts on the control slide (41) as a function of the flow speed of the damper medium in the closing direction.
2. Damper-valve device according to Claim 1, characterized in that, in relation to the flow path of the damper medium, the control slide (41) is arranged in series with respect to the damper valve (12; 20).
3. Damper-valve device according to Claim 1, characterized in that the control slide (41) is connected with its pressure-loaded surface (57) to a throttle point (55) which leads to the first damper-valve assembly (15; 17; 19; 31; 39).
4. Damper-valve device according to Claim 3, characterized in that the throttle point (55) is defined by the external diameter of the control slide (41).
5. Damper-valve device according to Claim 1, characterized in that the control slide (41) is held in the throughflow position by a spring (43).
6. Damper-valve device according to Claim 1, characterized in that a pressure-limiting valve (55) is connected in parallel to the throttle point (45; 55).
7. Damper-valve device according to Claim 6, characterized in that the pressure-limiting valve (59) is formed by a disc spring assembly (43; 61) which also holds the control slide (41) in the throughflow position.
8. Damper valve according to Claim 6, characterized in that the control slide (41) is held in the throughflow position independently of the pretensioning force which acts on the pressure-limiting valve.
9. Damper valve according to Claim 8, characterized in that the control slide (41) is mounted such that it can be displaced relative to the valve plate (64) of the pressure-limiting valve (59).
10. Damper valve according to Claim 9, characterized in that, in the throughflow position, the control slide (41) is supported axially on the valve plate (64) of the pressure-limiting valve (59).
11. Damper-valve device according to Claim 1, characterized in that a spring support (63) accommodates the spring (43) which holds the control slide (41) in the throughflow position.
12. Damper valve according to Claim 1, characterized in that the control slide (41) has a plastically deformable adjusting region (44).
13. Damper valve according to Claim 12, characterized in that the adjusting region (44) of the valve body (41) is formed by a reduction (41n) in the wall thickness.
14. Vibration damper having a damper-valve device according to Claim 4, characterized in that the throttle point (55) is defined by an inner wall (53) of a cylinder (3) of the vibration damper (1).
15. Vibration damper having a damper-valve device according to Claim 1, characterized in that the damper-valve device according to the invention is configured on a piston (7) of the vibration damper (1).
16. Vibration damper having a damper-valve device according to Claim 5, characterized in that the control slide (41) is supported on a piston nut (25) of the piston (7).
17. Vibration damper having a damper-valve device according to Claim 5, characterized in that the spring (43) which holds the control slide (41) in the throughflow position is configured independently of a valve spring (23) which pretensions the valve body (21) of the first damper-valve assembly (10) of the piston-side damper valve.
18. Damper-valve device for a vibration damper according to Claim 7, characterized in that the valve spring (23) for the first assembly (10) of the damper valve (12) fixes the assembly (41; 43; 63) which comprises the control slide (41) to the damper valve.
19. Vibration damper having a damper valve according to Claim 6, characterized in that the piston nut (25) clamps the spring support (63) and the control slide (41) to form a structural unit.
20. Vibration damper having a damper valve according to Claim 9, characterized in that a supporting ring (65), on which the control slide (41) is supported axially, is added to the structural unit (25; 63; 41).
21. Vibration damper having a damper valve according to Claim 20, characterized in that the supporting ring (65) is connected to the piston nut (25) in a torque-transmitting manner and is configured with turning-tool faces (65v).
22. Vibration damper having a damper-valve device according to Claim 14, characterized in that the damper-valve device is configured on the piston (7) and on the bottom valve (27).
23. Vibration damper having a damper-valve device according to Claim 22, characterized in that the control slide (41) on the bottom valve (27) assumes the closed position at a slower flow speed than the control slide (41) on the piston-side damper-valve device.

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